Orlando Cazalet-Hyams 54d544b831
[KeyInstr][Clang] Ret atom (#134652)
This patch is part of a stack that teaches Clang to generate Key Instructions
metadata for C and C++.

When returning a value, stores to the `retval` allocas and branches to `return`
block are put in the same atom group. They are both rank 1, which could in
theory introduce an extra step in some optimized code. This low risk currently
feels an acceptable for keeping the code a bit simpler (as opposed to adding
scaffolding to make the store rank 2).

In the case of a single return (no control flow) the return instruction inherits
the atom group of the branch to the return block when the blocks get folded
togather.

RFC:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668

The feature is only functional in LLVM if LLVM is built with CMake flag
LLVM_EXPERIMENTAL_KEY_INSTRUCTIONs. Eventually that flag will be removed.
2025-06-04 15:43:49 +01:00

184 lines
6.2 KiB
C

// RUN: %clang_cc1 -triple x86_64-linux-gnu -gkey-instructions -x c++ %s -debug-info-kind=line-tables-only -emit-llvm -o - \
// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
// RUN: %clang_cc1 -triple x86_64-linux-gnu -gkey-instructions -x c %s -debug-info-kind=line-tables-only -emit-llvm -o - \
// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
// Perennial question: should the inc be its own source atom or not
// (currently it is).
// TODO: See do.c and while.c regarding cmp and cond br groups.
void a(int A) {
// CHECK: entry:
// CHECK: store i32 0, ptr %i{{.*}}, !dbg [[G1R1:!.*]]
// CHECK: for.cond:
// CHECK: %cmp = icmp slt i32 %0, %1, !dbg [[G2R1:!.*]]
// CHECK: br i1 %cmp, label %for.body, label %for.end, !dbg [[G3R1:!.*]]
// TODO: The unconditional br is given an atom group here which is useful for
// O0. Since we're no longer targeting O0 we should reevaluate whether this
// adds any value.
// CHECK: for.body:
// CHECK-NEXT: br label %for.inc, !dbg [[G5R1:!.*]]
// CHECK: for.inc:
// CHECK: %inc = add{{.*}}, !dbg [[G4R2:!.*]]
// CHECK: store i32 %inc, ptr %i{{.*}}, !dbg [[G4R1:!.*]]
for (int i = 0; i < A; ++i) {
}
// CHECK: ret{{.*}}, !dbg [[RET:!.*]]
}
void b(int A) {
// CHECK: entry:
// CHECK: store i32 0, ptr %i{{.*}}, !dbg [[bG1R1:!.*]]
// CHECK: for.cond:
// CHECK: %cmp = icmp slt i32 %0, %1, !dbg [[bG2R1:!.*]]
// CHECK: br i1 %cmp, label %for.body, label %for.end, !dbg [[bG3R1:!.*]]
// CHECK: for.body:
// CHECK-NEXT: %2 = load i32, ptr %A.addr
// - If stmt atom:
// CHECK-NEXT: %cmp1 = icmp sgt i32 %2, 1, !dbg [[bG4R2:!.*]]
// CHECK-NEXT: br i1 %cmp1, label %if.then, label %if.end, !dbg [[bG4R1:!.*]]
// CHECK: if.then:
// CHECK-NEXT: br label %if.end
// - For closing brace.
// CHECK: if.end:
// CHECK-NEXT: br label %for.inc, !dbg [[bG6R1:!.*]]
// CHECK: for.inc:
// CHECK: %inc = add{{.*}}, !dbg [[bG5R2:!.*]]
// CHECK: store i32 %inc, ptr %i{{.*}}, !dbg [[bG5R1:!.*]]
for (int i = 0; i < A; ++i) {
if (A > 1)
;
}
// CHECK: ret{{.*}}, !dbg [[bRET:!.*]]
}
void c(int A) {
// CHECK: entry:
// CHECK: for.cond:
// CHECK-NEXT: %0 = load i32, ptr %A.addr
// - If stmt atom:
// CHECK-NEXT: %cmp = icmp sgt i32 %0, 1, !dbg [[cG1R2:!.*]]
// CHECK-NEXT: br i1 %cmp, label %if.then, label %if.end, !dbg [[cG1R1:!.*]]
// CHECK: if.then:
// CHECK-NEXT: br label %if.end
// - For closing brace.
// CHECK: if.end:
// CHECK-NEXT: br label %for.inc, !dbg [[cG3R1:!.*]]
// CHECK: for.inc:
// CHECK-NEXT: %1 = load i32, ptr %A.addr
// CHECK-NEXT: %inc = add{{.*}}, !dbg [[cG2R2:!.*]]
// CHECK-NEXT: store i32 %inc, ptr %A.addr{{.*}}, !dbg [[cG2R1:!.*]]
for (; /*no cond*/ ; ++A) {
if (A > 1)
;
}
}
void d() {
// - Check the `for` keyword gets an atom group.
// CHECK: entry:
// CHECK-NEXT: br label %for.cond
// CHECK: for.cond:
// CHECK: br label %for.cond, !dbg [[dG1R1:!.*]], !llvm.loop
for ( ; ; )
{
}
}
int x, i;
void ee();
void e() {
// - Check we assign an atom group to `for.body`s `br`, even without braces.
// - TODO: Investigate whether this is needed.
// CHECK: entry:
// CHECK: for.cond:
// CHECK-NEXT: %0 = load i32, ptr @i
// CHECK-NEXT: %cmp = icmp slt i32 %0, 3, !dbg [[eG1R1:!.*]]
// CHECK-NEXT: br i1 %cmp, label %for.body, label %for.end, !dbg [[eG2R1:!.*]]
// CHECK: for.body:
// CHECK-NEXT: %1 = load i32, ptr @i{{.*}}, !dbg [[eG3R2:!.*]]
// CHECK-NEXT: store i32 %1, ptr @x{{.*}}, !dbg [[eG3R1:!.*]]
// CHECK-NEXT: br label %for.inc, !dbg [[eG4R1:!.*]]
for (; i < 3; ee())
x = i;
// CHECK: ret{{.*}}, !dbg [[eRET:!.*]]
}
void f() {
// - Check the `continue` keyword gets an atom group.
// CHECK: entry:
// CHECK-NEXT: br label %for.cond
// CHECK: for.cond:
// CHECK: br label %for.cond, !dbg [[fG1R1:!.*]], !llvm.loop
for ( ; ; )
{
continue;
}
}
void g() {
// - Check the `break` keyword gets an atom group.
// CHECK: entry:
// CHECK-NEXT: br label %for.cond
// CHECK: for.cond:
// CHECK: br label %for.end, !dbg [[gG1R1:!.*]]
for ( ; ; )
{
break;
}
// CHECK: ret{{.*}}, !dbg [[gRET:!.*]]
}
// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
// CHECK: [[G5R1]] = !DILocation(line: 29,{{.*}} atomGroup: 5, atomRank: 1)
// CHECK: [[G4R2]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 2)
// CHECK: [[G4R1]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)
// CHECK: [[RET]] = !DILocation({{.*}}, atomGroup: 6, atomRank: 1)
// CHECK: [[bG1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
// CHECK: [[bG2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
// CHECK: [[bG3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
// CHECK: [[bG4R2]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 2)
// CHECK: [[bG4R1]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)
// CHECK: [[bG6R1]] = !DILocation(line: 58,{{.*}} atomGroup: 6, atomRank: 1)
// CHECK: [[bG5R2]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 2)
// CHECK: [[bG5R1]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 1)
// CHECK: [[bRET]] = !DILocation({{.*}}, atomGroup: 7, atomRank: 1)
// CHECK: [[cG1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
// CHECK: [[cG1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
// CHECK: [[cG3R1]] = !DILocation(line: 83,{{.*}} atomGroup: 3, atomRank: 1)
// CHECK: [[cG2R2]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
// CHECK: [[cG2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
// CHECK: [[dG1R1]] = !DILocation(line: 93, column: 3, scope: ![[#]], atomGroup: 1, atomRank: 1)
// CHECK: [[eG1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
// CHECK: [[eG2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
// CHECK: [[eG3R2]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 2)
// CHECK: [[eG3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
// CHECK: [[eG4R1]] = !DILocation(line: 115, column: 5, scope: ![[#]], atomGroup: 4, atomRank: 1)
// CHECK: [[eRET]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 1)
// CHECK: [[fG1R1]] = !DILocation(line: 129, column: 5, scope: ![[#]], atomGroup: 1, atomRank: 1)
// CHECK: [[gG1R1]] = !DILocation(line: 142, column: 5, scope: ![[#]], atomGroup: 1, atomRank: 1)
// CHECK: [[gRET]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)