[X86] Treat __start_*/__stop_* symbols as large #79909
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Followup to llvm#79884. The linker adds __start_foo/__stop_foo symbols pointing to the beginning/end of the foo section. These can be far away from text, so treat them as large symbols under the medium/large code models. Performance to access these is almost certainly not important.
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@llvm/pr-subscribers-backend-x86 Author: Arthur Eubanks (aeubanks) ChangesFollowup to #79884. The linker adds __start_foo/__stop_foo symbols pointing to the beginning/end of the foo section. These can be far away from text, so treat them as large symbols under the medium/large code models. Performance to access these is almost certainly not important. Full diff: https://github.com/llvm/llvm-project/pull/79909.diff 2 Files Affected:
diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 178d199836abe0..4258a76b54b92b 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -85,7 +85,11 @@ bool TargetMachine::isLargeGlobalValue(const GlobalValue *GVal) const {
getCodeModel() == CodeModel::Large) {
if (!GV->getValueType()->isSized())
return true;
- if (GV->isDeclaration() && GV->getName() == "__ehdr_start")
+ // Linker defined start/stop symbols can point to arbitrary points in the
+ // binary, so treat them as large.
+ if (GV->isDeclaration() && (GV->getName() == "__ehdr_start" ||
+ GV->getName().starts_with("__start_") ||
+ GV->getName().starts_with("__stop_")))
return true;
const DataLayout &DL = GV->getParent()->getDataLayout();
uint64_t Size = DL.getTypeSizeInBits(GV->getValueType()) / 8;
diff --git a/llvm/test/CodeGen/X86/code-model-elf.ll b/llvm/test/CodeGen/X86/code-model-elf.ll
index 4bc917a3b3aa6a..71a6a310906e2e 100644
--- a/llvm/test/CodeGen/X86/code-model-elf.ll
+++ b/llvm/test/CodeGen/X86/code-model-elf.ll
@@ -58,6 +58,8 @@ target triple = "x86_64--linux"
@forced_small_data = dso_local global [10 x i32] zeroinitializer, code_model "small", align 16
@forced_large_data = dso_local global [10 x i32] zeroinitializer, code_model "large", align 16
@__ehdr_start = external dso_local global i8
+@__start_foo = external dso_local global i8
+@__stop_foo = external dso_local global i8
define dso_local ptr @lea_static_data() #0 {
; SMALL-STATIC-LABEL: lea_static_data:
@@ -858,6 +860,120 @@ define dso_local ptr @lea_ehdr_start() #0 {
ret ptr @__ehdr_start
}
+define dso_local ptr @lea_start_foo() #0 {
+; SMALL-STATIC-LABEL: lea_start_foo:
+; SMALL-STATIC: # %bb.0:
+; SMALL-STATIC-NEXT: movl $__start_foo, %eax
+; SMALL-STATIC-NEXT: retq
+;
+; MEDIUM-STATIC-LABEL: lea_start_foo:
+; MEDIUM-STATIC: # %bb.0:
+; MEDIUM-STATIC-NEXT: movabsq $__start_foo, %rax
+; MEDIUM-STATIC-NEXT: retq
+;
+; LARGE-STATIC-LABEL: lea_start_foo:
+; LARGE-STATIC: # %bb.0:
+; LARGE-STATIC-NEXT: movabsq $__start_foo, %rax
+; LARGE-STATIC-NEXT: retq
+;
+; SMALL-PIC-LABEL: lea_start_foo:
+; SMALL-PIC: # %bb.0:
+; SMALL-PIC-NEXT: leaq __start_foo(%rip), %rax
+; SMALL-PIC-NEXT: retq
+;
+; MEDIUM-SMALL-DATA-PIC-LABEL: lea_start_foo:
+; MEDIUM-SMALL-DATA-PIC: # %bb.0:
+; MEDIUM-SMALL-DATA-PIC-NEXT: leaq _GLOBAL_OFFSET_TABLE_(%rip), %rcx
+; MEDIUM-SMALL-DATA-PIC-NEXT: movabsq $__start_foo@GOTOFF, %rax
+; MEDIUM-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
+; MEDIUM-SMALL-DATA-PIC-NEXT: retq
+;
+; MEDIUM-PIC-LABEL: lea_start_foo:
+; MEDIUM-PIC: # %bb.0:
+; MEDIUM-PIC-NEXT: leaq _GLOBAL_OFFSET_TABLE_(%rip), %rcx
+; MEDIUM-PIC-NEXT: movabsq $__start_foo@GOTOFF, %rax
+; MEDIUM-PIC-NEXT: addq %rcx, %rax
+; MEDIUM-PIC-NEXT: retq
+;
+; LARGE-PIC-LABEL: lea_start_foo:
+; LARGE-PIC: # %bb.0:
+; LARGE-PIC-NEXT: .L14$pb:
+; LARGE-PIC-NEXT: leaq .L14$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L14$pb, %rcx
+; LARGE-PIC-NEXT: addq %rax, %rcx
+; LARGE-PIC-NEXT: movabsq $__start_foo@GOTOFF, %rax
+; LARGE-PIC-NEXT: addq %rcx, %rax
+; LARGE-PIC-NEXT: retq
+;
+; LARGE-SMALL-DATA-PIC-LABEL: lea_start_foo:
+; LARGE-SMALL-DATA-PIC: # %bb.0:
+; LARGE-SMALL-DATA-PIC-NEXT: .L14$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L14$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L14$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $__start_foo@GOTOFF, %rax
+; LARGE-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
+; LARGE-SMALL-DATA-PIC-NEXT: retq
+ ret ptr @__start_foo
+}
+
+define dso_local ptr @lea_stop_foo() #0 {
+; SMALL-STATIC-LABEL: lea_stop_foo:
+; SMALL-STATIC: # %bb.0:
+; SMALL-STATIC-NEXT: movl $__stop_foo, %eax
+; SMALL-STATIC-NEXT: retq
+;
+; MEDIUM-STATIC-LABEL: lea_stop_foo:
+; MEDIUM-STATIC: # %bb.0:
+; MEDIUM-STATIC-NEXT: movabsq $__stop_foo, %rax
+; MEDIUM-STATIC-NEXT: retq
+;
+; LARGE-STATIC-LABEL: lea_stop_foo:
+; LARGE-STATIC: # %bb.0:
+; LARGE-STATIC-NEXT: movabsq $__stop_foo, %rax
+; LARGE-STATIC-NEXT: retq
+;
+; SMALL-PIC-LABEL: lea_stop_foo:
+; SMALL-PIC: # %bb.0:
+; SMALL-PIC-NEXT: leaq __stop_foo(%rip), %rax
+; SMALL-PIC-NEXT: retq
+;
+; MEDIUM-SMALL-DATA-PIC-LABEL: lea_stop_foo:
+; MEDIUM-SMALL-DATA-PIC: # %bb.0:
+; MEDIUM-SMALL-DATA-PIC-NEXT: leaq _GLOBAL_OFFSET_TABLE_(%rip), %rcx
+; MEDIUM-SMALL-DATA-PIC-NEXT: movabsq $__stop_foo@GOTOFF, %rax
+; MEDIUM-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
+; MEDIUM-SMALL-DATA-PIC-NEXT: retq
+;
+; MEDIUM-PIC-LABEL: lea_stop_foo:
+; MEDIUM-PIC: # %bb.0:
+; MEDIUM-PIC-NEXT: leaq _GLOBAL_OFFSET_TABLE_(%rip), %rcx
+; MEDIUM-PIC-NEXT: movabsq $__stop_foo@GOTOFF, %rax
+; MEDIUM-PIC-NEXT: addq %rcx, %rax
+; MEDIUM-PIC-NEXT: retq
+;
+; LARGE-PIC-LABEL: lea_stop_foo:
+; LARGE-PIC: # %bb.0:
+; LARGE-PIC-NEXT: .L15$pb:
+; LARGE-PIC-NEXT: leaq .L15$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L15$pb, %rcx
+; LARGE-PIC-NEXT: addq %rax, %rcx
+; LARGE-PIC-NEXT: movabsq $__stop_foo@GOTOFF, %rax
+; LARGE-PIC-NEXT: addq %rcx, %rax
+; LARGE-PIC-NEXT: retq
+;
+; LARGE-SMALL-DATA-PIC-LABEL: lea_stop_foo:
+; LARGE-SMALL-DATA-PIC: # %bb.0:
+; LARGE-SMALL-DATA-PIC-NEXT: .L15$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L15$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L15$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $__stop_foo@GOTOFF, %rax
+; LARGE-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
+; LARGE-SMALL-DATA-PIC-NEXT: retq
+ ret ptr @__stop_foo
+}
+
define dso_local void @global_fn() #0 {
; CHECK-LABEL: global_fn:
; CHECK: # %bb.0:
@@ -919,9 +1035,9 @@ define dso_local ptr @lea_static_fn() #0 {
;
; LARGE-PIC-LABEL: lea_static_fn:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L17$pb:
-; LARGE-PIC-NEXT: leaq .L17$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L17$pb, %rcx
+; LARGE-PIC-NEXT: .L19$pb:
+; LARGE-PIC-NEXT: leaq .L19$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L19$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq $static_fn@GOTOFF, %rax
; LARGE-PIC-NEXT: addq %rcx, %rax
@@ -929,9 +1045,9 @@ define dso_local ptr @lea_static_fn() #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: lea_static_fn:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L17$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L17$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L17$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L19$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L19$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L19$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq $static_fn@GOTOFF, %rax
; LARGE-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
@@ -972,9 +1088,9 @@ define dso_local ptr @lea_global_fn() #0 {
;
; LARGE-PIC-LABEL: lea_global_fn:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L18$pb:
-; LARGE-PIC-NEXT: leaq .L18$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L18$pb, %rcx
+; LARGE-PIC-NEXT: .L20$pb:
+; LARGE-PIC-NEXT: leaq .L20$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L20$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq $global_fn@GOTOFF, %rax
; LARGE-PIC-NEXT: addq %rcx, %rax
@@ -982,9 +1098,9 @@ define dso_local ptr @lea_global_fn() #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: lea_global_fn:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L18$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L18$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L18$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L20$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L20$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L20$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq $global_fn@GOTOFF, %rax
; LARGE-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
@@ -1025,9 +1141,9 @@ define dso_local ptr @lea_extern_fn() #0 {
;
; LARGE-PIC-LABEL: lea_extern_fn:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L19$pb:
-; LARGE-PIC-NEXT: leaq .L19$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L19$pb, %rcx
+; LARGE-PIC-NEXT: .L21$pb:
+; LARGE-PIC-NEXT: leaq .L21$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L21$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq $extern_fn@GOT, %rax
; LARGE-PIC-NEXT: movq (%rcx,%rax), %rax
@@ -1035,9 +1151,9 @@ define dso_local ptr @lea_extern_fn() #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: lea_extern_fn:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L19$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L19$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L19$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L21$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L21$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L21$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq $extern_fn@GOT, %rax
; LARGE-SMALL-DATA-PIC-NEXT: movq (%rcx,%rax), %rax
@@ -1078,9 +1194,9 @@ define dso_local ptr @lea_ifunc() #0 {
;
; LARGE-PIC-LABEL: lea_ifunc:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L20$pb:
-; LARGE-PIC-NEXT: leaq .L20$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L20$pb, %rcx
+; LARGE-PIC-NEXT: .L22$pb:
+; LARGE-PIC-NEXT: leaq .L22$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L22$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq $ifunc_func@GOT, %rax
; LARGE-PIC-NEXT: movq (%rcx,%rax), %rax
@@ -1088,9 +1204,9 @@ define dso_local ptr @lea_ifunc() #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: lea_ifunc:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L20$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L20$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L20$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L22$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L22$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L22$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq $ifunc_func@GOT, %rax
; LARGE-SMALL-DATA-PIC-NEXT: movq (%rcx,%rax), %rax
@@ -1131,9 +1247,9 @@ define dso_local ptr @lea_dso_local_ifunc() #0 {
;
; LARGE-PIC-LABEL: lea_dso_local_ifunc:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L21$pb:
-; LARGE-PIC-NEXT: leaq .L21$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L21$pb, %rcx
+; LARGE-PIC-NEXT: .L23$pb:
+; LARGE-PIC-NEXT: leaq .L23$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L23$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq $dso_local_ifunc_func@GOTOFF, %rax
; LARGE-PIC-NEXT: addq %rcx, %rax
@@ -1141,9 +1257,9 @@ define dso_local ptr @lea_dso_local_ifunc() #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: lea_dso_local_ifunc:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L21$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L21$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L21$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L23$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L23$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L23$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq $dso_local_ifunc_func@GOTOFF, %rax
; LARGE-SMALL-DATA-PIC-NEXT: addq %rcx, %rax
@@ -1218,9 +1334,9 @@ define dso_local float @load_constant_pool(float %x) #0 {
;
; LARGE-PIC-LABEL: load_constant_pool:
; LARGE-PIC: # %bb.0:
-; LARGE-PIC-NEXT: .L23$pb:
-; LARGE-PIC-NEXT: leaq .L23$pb(%rip), %rax
-; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L23$pb, %rcx
+; LARGE-PIC-NEXT: .L25$pb:
+; LARGE-PIC-NEXT: leaq .L25$pb(%rip), %rax
+; LARGE-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L25$pb, %rcx
; LARGE-PIC-NEXT: addq %rax, %rcx
; LARGE-PIC-NEXT: movabsq ${{\.?LCPI[0-9]+_[0-9]+}}@GOTOFF, %rax
; LARGE-PIC-NEXT: addss (%rcx,%rax), %xmm0
@@ -1228,9 +1344,9 @@ define dso_local float @load_constant_pool(float %x) #0 {
;
; LARGE-SMALL-DATA-PIC-LABEL: load_constant_pool:
; LARGE-SMALL-DATA-PIC: # %bb.0:
-; LARGE-SMALL-DATA-PIC-NEXT: .L23$pb:
-; LARGE-SMALL-DATA-PIC-NEXT: leaq .L23$pb(%rip), %rax
-; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L23$pb, %rcx
+; LARGE-SMALL-DATA-PIC-NEXT: .L25$pb:
+; LARGE-SMALL-DATA-PIC-NEXT: leaq .L25$pb(%rip), %rax
+; LARGE-SMALL-DATA-PIC-NEXT: movabsq $_GLOBAL_OFFSET_TABLE_-.L25$pb, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: addq %rax, %rcx
; LARGE-SMALL-DATA-PIC-NEXT: movabsq ${{\.?LCPI[0-9]+_[0-9]+}}@GOTOFF, %rax
; LARGE-SMALL-DATA-PIC-NEXT: addss (%rcx,%rax), %xmm0
|
MaskRay
approved these changes
Jan 29, 2024
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Followup to #79884.
The linker adds __start_foo/__stop_foo symbols pointing to the beginning/end of the foo section. These can be far away from text, so treat them as large symbols under the medium/large code models. Performance to access these is almost certainly not important.