Skip to content

[AArch64] Fallback to PRFUM for PRFM with negative or unaligned offset #166756

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 10, 2025
Merged

[AArch64] Fallback to PRFUM for PRFM with negative or unaligned offset #166756

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions llvm/lib/Target/AArch64/AArch64InstrInfo.td
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4444,6 +4444,11 @@ defm PRFUM : PrefetchUnscaled<0b11, 0, 0b10, "prfum",
[(AArch64Prefetch timm:$Rt,
(am_unscaled64 GPR64sp:$Rn, simm9:$offset))]>;

// PRFM falls back to PRFUM for negative or unaligned offsets (not a multiple
// of 8).
def : InstAlias<"prfm $Rt, [$Rn, $offset]",
(PRFUMi prfop:$Rt, GPR64sp:$Rn, simm9_offset_fb64:$offset), 0>;

//---
// (unscaled immediate, unprivileged)
defm LDTRX : LoadUnprivileged<0b11, 0, 0b01, GPR64, "ldtr">;
Expand Down
44 changes: 44 additions & 0 deletions llvm/test/MC/AArch64/prfum.s
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
// RUN: llvm-mc -triple=aarch64 -show-encoding --print-imm-hex=false < %s \
// RUN: | FileCheck %s --check-prefixes=CHECK-ENCODING,CHECK-INST
// RUN: llvm-mc -triple=aarch64 -filetype=obj < %s \
// RUN: | llvm-objdump -d --print-imm-hex=false - | FileCheck %s --check-prefix=CHECK-INST
// Disassemble encoding and check the re-encoding (-show-encoding) matches.
// RUN: llvm-mc -triple=aarch64 -show-encoding < %s \
// RUN: | sed '/.text/d' | sed 's/.*encoding: //g' \
// RUN: | llvm-mc -triple=aarch64 -disassemble -show-encoding --print-imm-hex=false \
// RUN: | FileCheck %s --check-prefixes=CHECK-ENCODING,CHECK-INST

// PRFM falls back to PRFUM for negative or unaligned offsets (not a multiple
// of 8).

prfm pldl1keep, [x0, #-256]
// CHECK-INST: prfum pldl1keep, [x0, #-256]
// CHECK-ENCODING: [0x00,0x00,0x90,0xf8]

prfm pldl1keep, [x0, #-8]
// CHECK-INST: prfum pldl1keep, [x0, #-8]
// CHECK-ENCODING: [0x00,0x80,0x9f,0xf8]

prfm pldl1keep, [x0, #-1]
// CHECK-INST: prfum pldl1keep, [x0, #-1]
// CHECK-ENCODING: [0x00,0xf0,0x9f,0xf8]

prfm pldl1keep, [x0, #0]
// CHECK-INST: prfm pldl1keep, [x0]
// CHECK-ENCODING: [0x00,0x00,0x80,0xf9]

prfm pldl1keep, [x0, #1]
// CHECK-INST: prfum pldl1keep, [x0, #1]
// CHECK-ENCODING: [0x00,0x10,0x80,0xf8]

prfm pldl1keep, [x0, #8]
// CHECK-INST: prfm pldl1keep, [x0, #8]
// CHECK-ENCODING: [0x00,0x04,0x80,0xf9]

prfm pldl1keep, [x0, #255]
// CHECK-INST: prfum pldl1keep, [x0, #255]
// CHECK-ENCODING: [0x00,0xf0,0x8f,0xf8]

prfm pldl1keep, [x0, #256]
// CHECK-INST: prfm pldl1keep, [x0, #256]
// CHECK-ENCODING: [0x00,0x80,0x80,0xf9]