[AArch64] Set predicates for FP/SIMD InstAliases #79033

ostannard · 2024-01-22T18:46:24Z

These are aliases for instructions which are are only available when the fp-armv8 or neon features are enabled, so their predicates should be set appropriately.

llvmbot · 2024-01-22T18:46:43Z

@llvm/pr-subscribers-mc

@llvm/pr-subscribers-backend-aarch64

Author: None (ostannard)

Changes

These are aliases for instructions which are are only available when the fp-armv8 or neon features are enabled, so their predicates should be set appropriately.

Full diff: https://github.com/llvm/llvm-project/pull/79033.diff

2 Files Affected:

(modified) llvm/lib/Target/AArch64/AArch64InstrInfo.td (+23-1)
(modified) llvm/test/MC/AArch64/no-fp-errors.s (+170)

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.td b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
index c63f23bda6805a5..cdd9ad5f7e442e8 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
@@ -3520,6 +3520,7 @@ def : InstAlias<"ldr $Rt, [$Rn, $offset]",
                 (LDURXi GPR64:$Rt, GPR64sp:$Rn, simm9_offset_fb64:$offset), 0>;
 def : InstAlias<"ldr $Rt, [$Rn, $offset]",
                 (LDURWi GPR32:$Rt, GPR64sp:$Rn, simm9_offset_fb32:$offset), 0>;
+let Predicates = [HasFPARMv8] in {
 def : InstAlias<"ldr $Rt, [$Rn, $offset]",
                 (LDURBi FPR8Op:$Rt, GPR64sp:$Rn, simm9_offset_fb8:$offset), 0>;
 def : InstAlias<"ldr $Rt, [$Rn, $offset]",
@@ -3530,6 +3531,7 @@ def : InstAlias<"ldr $Rt, [$Rn, $offset]",
                 (LDURDi FPR64Op:$Rt, GPR64sp:$Rn, simm9_offset_fb64:$offset), 0>;
 def : InstAlias<"ldr $Rt, [$Rn, $offset]",
                (LDURQi FPR128Op:$Rt, GPR64sp:$Rn, simm9_offset_fb128:$offset), 0>;
+}
 
 // zextload -> i64
 def : Pat<(i64 (zextloadi8 (am_unscaled8 GPR64sp:$Rn, simm9:$offset))),
@@ -4163,6 +4165,7 @@ def : InstAlias<"str $Rt, [$Rn, $offset]",
                 (STURXi GPR64:$Rt, GPR64sp:$Rn, simm9_offset_fb64:$offset), 0>;
 def : InstAlias<"str $Rt, [$Rn, $offset]",
                 (STURWi GPR32:$Rt, GPR64sp:$Rn, simm9_offset_fb32:$offset), 0>;
+let Predicates = [HasFPARMv8] in {
 def : InstAlias<"str $Rt, [$Rn, $offset]",
                 (STURBi FPR8Op:$Rt, GPR64sp:$Rn, simm9_offset_fb8:$offset), 0>;
 def : InstAlias<"str $Rt, [$Rn, $offset]",
@@ -4173,6 +4176,7 @@ def : InstAlias<"str $Rt, [$Rn, $offset]",
                 (STURDi FPR64Op:$Rt, GPR64sp:$Rn, simm9_offset_fb64:$offset), 0>;
 def : InstAlias<"str $Rt, [$Rn, $offset]",
                 (STURQi FPR128Op:$Rt, GPR64sp:$Rn, simm9_offset_fb128:$offset), 0>;
+}
 
 def : InstAlias<"strb $Rt, [$Rn, $offset]",
                 (STURBBi GPR32:$Rt, GPR64sp:$Rn, simm9_offset_fb8:$offset), 0>;
@@ -4583,8 +4587,10 @@ def FMOVD0 : Pseudo<(outs FPR64:$Rd), (ins), [(set f64:$Rd, (fpimm0))]>,
 // Similarly add aliases
 def : InstAlias<"fmov $Rd, #0.0", (FMOVWHr FPR16:$Rd, WZR), 0>,
     Requires<[HasFullFP16]>;
+let Predicates = [HasFPARMv8] in {
 def : InstAlias<"fmov $Rd, #0.0", (FMOVWSr FPR32:$Rd, WZR), 0>;
 def : InstAlias<"fmov $Rd, #0.0", (FMOVXDr FPR64:$Rd, XZR), 0>;
+}
 
 def : Pat<(bf16 fpimm0),
           (FMOVH0)>;
@@ -5026,10 +5032,12 @@ defm NEG    : SIMDTwoVectorBHSD<1, 0b01011, "neg",
                                UnOpFrag<(sub immAllZerosV, node:$LHS)> >;
 defm NOT    : SIMDTwoVectorB<1, 0b00, 0b00101, "not", vnot>;
 // Aliases for MVN -> NOT.
+let Predicates = [HasNEON] in {
 def : InstAlias<"mvn{ $Vd.8b, $Vn.8b|.8b $Vd, $Vn}",
                 (NOTv8i8 V64:$Vd, V64:$Vn)>;
 def : InstAlias<"mvn{ $Vd.16b, $Vn.16b|.16b $Vd, $Vn}",
                 (NOTv16i8 V128:$Vd, V128:$Vn)>;
+}
 
 def : Pat<(vnot (v4i16 V64:$Rn)),  (NOTv8i8  V64:$Rn)>;
 def : Pat<(vnot (v8i16 V128:$Rn)), (NOTv16i8 V128:$Rn)>;
@@ -5292,6 +5300,7 @@ def : Pat<(AArch64bsp (v4i32 V128:$Rd), V128:$Rn, V128:$Rm),
 def : Pat<(AArch64bsp (v2i64 V128:$Rd), V128:$Rn, V128:$Rm),
           (BSPv16i8 V128:$Rd, V128:$Rn, V128:$Rm)>;
 
+let Predicates = [HasNEON] in {
 def : InstAlias<"mov{\t$dst.16b, $src.16b|.16b\t$dst, $src}",
                 (ORRv16i8 V128:$dst, V128:$src, V128:$src), 1>;
 def : InstAlias<"mov{\t$dst.8h, $src.8h|.8h\t$dst, $src}",
@@ -5469,6 +5478,7 @@ def : InstAlias<"{faclt\t$dst.4s, $src1.4s, $src2.4s" #
 def : InstAlias<"{faclt\t$dst.2d, $src1.2d, $src2.2d" #
                 "|faclt.2d\t$dst, $src1, $src2}",
                 (FACGTv2f64 V128:$dst, V128:$src2, V128:$src1), 0>;
+}
 
 //===----------------------------------------------------------------------===//
 // Advanced SIMD three scalar instructions.
@@ -5531,6 +5541,7 @@ defm : FMULScalarFromIndexedLane0Patterns<"FMULX", "16", "32", "64",
                                           int_aarch64_neon_fmulx,
                                           [HasNEONorSME]>;
 
+let Predicates = [HasNEON] in {
 def : InstAlias<"cmls $dst, $src1, $src2",
                 (CMHSv1i64 FPR64:$dst, FPR64:$src2, FPR64:$src1), 0>;
 def : InstAlias<"cmle $dst, $src1, $src2",
@@ -5539,6 +5550,8 @@ def : InstAlias<"cmlo $dst, $src1, $src2",
                 (CMHIv1i64 FPR64:$dst, FPR64:$src2, FPR64:$src1), 0>;
 def : InstAlias<"cmlt $dst, $src1, $src2",
                 (CMGTv1i64 FPR64:$dst, FPR64:$src2, FPR64:$src1), 0>;
+}
+let Predicates = [HasFPARMv8] in {
 def : InstAlias<"fcmle $dst, $src1, $src2",
                 (FCMGE32 FPR32:$dst, FPR32:$src2, FPR32:$src1), 0>;
 def : InstAlias<"fcmle $dst, $src1, $src2",
@@ -5555,6 +5568,7 @@ def : InstAlias<"faclt $dst, $src1, $src2",
                 (FACGT32 FPR32:$dst, FPR32:$src2, FPR32:$src1), 0>;
 def : InstAlias<"faclt $dst, $src1, $src2",
                 (FACGT64 FPR64:$dst, FPR64:$src2, FPR64:$src1), 0>;
+}
 
 //===----------------------------------------------------------------------===//
 // Advanced SIMD three scalar instructions (mixed operands).
@@ -7001,6 +7015,7 @@ defm BIC : SIMDModifiedImmVectorShiftTied<1, 0b11, 0b01, "bic", AArch64bici>;
 // AdvSIMD ORR
 defm ORR : SIMDModifiedImmVectorShiftTied<0, 0b11, 0b01, "orr", AArch64orri>;
 
+let Predicates = [HasNEON] in {
 def : InstAlias<"bic $Vd.4h, $imm", (BICv4i16 V64:$Vd,  imm0_255:$imm, 0)>;
 def : InstAlias<"bic $Vd.8h, $imm", (BICv8i16 V128:$Vd, imm0_255:$imm, 0)>;
 def : InstAlias<"bic $Vd.2s, $imm", (BICv2i32 V64:$Vd,  imm0_255:$imm, 0)>;
@@ -7020,6 +7035,7 @@ def : InstAlias<"orr.4h $Vd, $imm", (ORRv4i16 V64:$Vd,  imm0_255:$imm, 0)>;
 def : InstAlias<"orr.8h $Vd, $imm", (ORRv8i16 V128:$Vd, imm0_255:$imm, 0)>;
 def : InstAlias<"orr.2s $Vd, $imm", (ORRv2i32 V64:$Vd,  imm0_255:$imm, 0)>;
 def : InstAlias<"orr.4s $Vd, $imm", (ORRv4i32 V128:$Vd, imm0_255:$imm, 0)>;
+}
 
 // AdvSIMD FMOV
 def FMOVv2f64_ns : SIMDModifiedImmVectorNoShift<1, 1, 0, 0b1111, V128, fpimm8,
@@ -7103,6 +7119,7 @@ let Predicates = [HasNEON] in {
                             ssub)>;
 }
 
+let Predicates = [HasNEON] in {
 def : InstAlias<"movi $Vd.4h, $imm", (MOVIv4i16 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"movi $Vd.8h, $imm", (MOVIv8i16 V128:$Vd, imm0_255:$imm, 0), 0>;
 def : InstAlias<"movi $Vd.2s, $imm", (MOVIv2i32 V64:$Vd,  imm0_255:$imm, 0), 0>;
@@ -7112,6 +7129,7 @@ def : InstAlias<"movi.4h $Vd, $imm", (MOVIv4i16 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"movi.8h $Vd, $imm", (MOVIv8i16 V128:$Vd, imm0_255:$imm, 0), 0>;
 def : InstAlias<"movi.2s $Vd, $imm", (MOVIv2i32 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"movi.4s $Vd, $imm", (MOVIv4i32 V128:$Vd, imm0_255:$imm, 0), 0>;
+}
 
 def : Pat<(v2i32 (AArch64movi_shift imm0_255:$imm8, (i32 imm:$shift))),
           (MOVIv2i32 imm0_255:$imm8, imm:$shift)>;
@@ -7147,6 +7165,7 @@ def MOVIv16b_ns  : SIMDModifiedImmVectorNoShift<1, 0, 0, 0b1110, V128, imm0_255,
 let isReMaterializable = 1, isAsCheapAsAMove = 1 in
 defm MVNI      : SIMDModifiedImmVectorShift<1, 0b10, 0b00, "mvni">;
 
+let Predicates = [HasNEON] in {
 def : InstAlias<"mvni $Vd.4h, $imm", (MVNIv4i16 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"mvni $Vd.8h, $imm", (MVNIv8i16 V128:$Vd, imm0_255:$imm, 0), 0>;
 def : InstAlias<"mvni $Vd.2s, $imm", (MVNIv2i32 V64:$Vd,  imm0_255:$imm, 0), 0>;
@@ -7156,6 +7175,7 @@ def : InstAlias<"mvni.4h $Vd, $imm", (MVNIv4i16 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"mvni.8h $Vd, $imm", (MVNIv8i16 V128:$Vd, imm0_255:$imm, 0), 0>;
 def : InstAlias<"mvni.2s $Vd, $imm", (MVNIv2i32 V64:$Vd,  imm0_255:$imm, 0), 0>;
 def : InstAlias<"mvni.4s $Vd, $imm", (MVNIv4i32 V128:$Vd, imm0_255:$imm, 0), 0>;
+}
 
 def : Pat<(v2i32 (AArch64mvni_shift imm0_255:$imm8, (i32 imm:$shift))),
           (MVNIv2i32 imm0_255:$imm8, imm:$shift)>;
@@ -7643,6 +7663,7 @@ def : Pat<(v2i64 (zext   (v2i32 (extract_high_v4i32 (v4i32 V128:$Rn)) ))),
 def : Pat<(v2i64 (sext   (v2i32 (extract_high_v4i32 (v4i32 V128:$Rn)) ))),
           (SSHLLv4i32_shift V128:$Rn, (i32 0))>;
 
+let Predicates = [HasNEON] in {
 // Vector shift sxtl aliases
 def : InstAlias<"sxtl.8h $dst, $src1",
                 (SSHLLv8i8_shift V128:$dst, V64:$src1, 0)>;
@@ -7698,6 +7719,7 @@ def : InstAlias<"uxtl2.2d $dst, $src1",
                 (USHLLv4i32_shift V128:$dst, V128:$src1, 0)>;
 def : InstAlias<"uxtl2 $dst.2d, $src1.4s",
                 (USHLLv4i32_shift V128:$dst, V128:$src1, 0)>;
+}
 
 // If an integer is about to be converted to a floating point value,
 // just load it on the floating point unit.
@@ -8146,7 +8168,7 @@ def AESIMCrr : AESInst<    0b0111, "aesimc", int_aarch64_crypto_aesimc>;
 
 // Pseudo instructions for AESMCrr/AESIMCrr with a register constraint required
 // for AES fusion on some CPUs.
-let hasSideEffects = 0, mayStore = 0, mayLoad = 0 in {
+let hasSideEffects = 0, mayStore = 0, mayLoad = 0, Predicates = [HasAES] in {
 def AESMCrrTied: Pseudo<(outs V128:$Rd), (ins V128:$Rn), [], "$Rn = $Rd">,
                         Sched<[WriteVq]>;
 def AESIMCrrTied: Pseudo<(outs V128:$Rd), (ins V128:$Rn), [], "$Rn = $Rd">,
diff --git a/llvm/test/MC/AArch64/no-fp-errors.s b/llvm/test/MC/AArch64/no-fp-errors.s
index 1595ba4798b082d..9fe3cba83e25513 100644
--- a/llvm/test/MC/AArch64/no-fp-errors.s
+++ b/llvm/test/MC/AArch64/no-fp-errors.s
@@ -191,3 +191,173 @@ label:
 // CHECK: [[@LINE-1]]:7: error: expected writable system register or pstate
   msr FPSR, x0
 // CHECK: [[@LINE-1]]:7: error: expected writable system register or pstate
+
+  ldr s0, [x0, #1]
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  str q0, [x0, #1]
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+
+  fmov s0, #0.0
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  fmov d0, #0.0
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+
+  mvn v0.8b, v1.8b
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvn v0.16b, v1.16b
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  mov v0.16b, v1.16b
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.8h, v1.8h
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.4s, v1.4s
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.2d, v1.2d
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  mov v0.8b, v1.8b
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.4h, v1.4h
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.2s, v1.2s
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mov v0.1d, v1.1d
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  faclt v0.4h, v1.4h, v2.4h
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fullfp16 neon
+  faclt v0.8h, v1.8h, v2.8h
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fullfp16 neon
+  faclt v0.2s, v1.2s, v2.2s
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  faclt v0.4s, v1.4s, v2.4s
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  faclt v0.2d, v1.2d, v2.2d
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  cmls d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  cmle d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  cmlo d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  cmlt d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  fcmle s0, s1, s2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  fcmle d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  fcmlt s0, s1, s2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  fcmlt d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  facle s0, s1, s2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  facle d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  faclt s0, s1, s2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+  faclt d0, d1, d2
+// CHECK: [[@LINE-1]]:3: error: instruction requires: fp-armv8
+
+  bic v0.4h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic v0.8h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic v0.2s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic v0.4s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  bic.4h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic.8h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic.2s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  bic.4s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  orr v0.4h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr v0.8h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr v0.2s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr v0.4s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  orr.4h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr.8h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr.2s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  orr.4s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  movi v0.4h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi v0.8h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi v0.2s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi v0.4s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  movi.4h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi.8h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi.2s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  movi.4s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  mvni v0.4h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni v0.8h, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni v0.2s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni v0.4s, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  mvni.4h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni.8h v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni.2s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  mvni.4s v0, #42
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  sxtl.8h v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  sxtl.4s v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  sxtl.2d v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  sxtl2.8h v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  sxtl2.4s v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  sxtl2.2d v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  uxtl.8h v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  uxtl.4s v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  uxtl.2d v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+
+  uxtl2.8h v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  uxtl2.4s v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon
+  uxtl2.2d v0, v1
+// CHECK: [[@LINE-1]]:3: error: instruction requires: neon

ostannard · 2024-01-22T18:47:25Z

Script used to find aliases with missing predicates: https://gist.github.com/ostannard/a919cf7c0da5a6971c1e345be1928ef0
Which depends on this tablegen patch: #79028

davemgreen · 2024-01-31T14:57:04Z

What do you think about the -mgeneral-regs-only issue? It worries me a bit to be honest, but this might not be making things a whole lot worse than they already are.

ostannard · 2024-02-05T12:59:30Z

I think that we don't currently support -mgeneral-regs-only in the same way that GCC does, so that shouldn't prevent us from handling things consistently. The instructions affected by this change are a random mix, I wouldn't expect this bug to be "useful" to anyone currently using -mgeneral-regs-only with clang.

As for how we could implement -mgeneral-regs-only, I think we'd need a way to have different Subtargets for the code-generation and assembler. I don't know exactly how that would work, but it would probably be a big change.

davemgreen · 2024-02-06T12:03:14Z

I think that we don't currently support -mgeneral-regs-only in the same way that GCC does, so that shouldn't prevent us from handling things consistently. The instructions affected by this change are a random mix, I wouldn't expect this bug to be "useful" to anyone currently using -mgeneral-regs-only with clang.

Yeah it's about whether it makes using a feature that people are already using even worse. If they are already relying on it then there is a limit to how much we can just say "it is not supported".

I don't think these aliases should be too much of a problem though, and we have the workaround you mentioned in #77817 (comment).

As for how we could implement -mgeneral-regs-only, I think we'd need a way to have different Subtargets for the code-generation and assembler. I don't know exactly how that would work, but it would probably be a big change.

This might be useful for the isNeonAvailable predicates too, which were apparently to allow neon inline assembly in streaming sve functions.

[AArch64] Set predicates for FP/SIMD InstAliases

961ef73

These are aliases for instructions which are are only available when the fp-armv8 or neon features are enabled, so their predicates should be set appropriately.

ostannard added backend:AArch64 mc Machine (object) code labels Jan 22, 2024

ostannard requested a review from davemgreen January 22, 2024 18:46

davemgreen approved these changes Feb 6, 2024

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ostannard merged commit 54c29e0 into llvm:main Feb 6, 2024
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[AArch64] Set predicates for FP/SIMD InstAliases #79033

[AArch64] Set predicates for FP/SIMD InstAliases #79033

ostannard commented Jan 22, 2024

llvmbot commented Jan 22, 2024 •

edited

ostannard commented Jan 22, 2024

davemgreen commented Jan 31, 2024

ostannard commented Feb 5, 2024

davemgreen commented Feb 6, 2024

[AArch64] Set predicates for FP/SIMD InstAliases #79033

[AArch64] Set predicates for FP/SIMD InstAliases #79033

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ostannard commented Jan 22, 2024

llvmbot commented Jan 22, 2024 • edited

ostannard commented Jan 22, 2024

davemgreen commented Jan 31, 2024

ostannard commented Feb 5, 2024

davemgreen commented Feb 6, 2024

llvmbot commented Jan 22, 2024 •

edited