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SafeStack: Re-enable SafeStack coloring optimization 

This was disabled in 2acea2786b as a
work-around for Issue #31491.  I've reduced the test case from that bug
and confirmed that it is now fixed.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D120866
This commit is contained in:
Tom Stellard 2022-03-08 15:10:39 -08:00
parent 8bdbcfe7d8
commit fb616c9b31
2 changed files with 44 additions and 2 deletions
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3
llvm/lib/CodeGen/SafeStack.cpp
View File

@ -97,10 +97,9 @@ static cl::opt<bool>
SafeStackUsePointerAddress("safestack-use-pointer-address",
cl::init(false), cl::Hidden);
// Disabled by default due to PR32143.
static cl::opt<bool> ClColoring("safe-stack-coloring",
cl::desc("enable safe stack coloring"),
cl::Hidden, cl::init(false));
cl::Hidden, cl::init(true));
namespace {

43
llvm/test/Transforms/SafeStack/X86/coloring2.ll
View File

@ -513,9 +513,52 @@ l2:
br label %l2
}
; This test checks for a bug where the stack coloring algorithm was not tracking
; the live range of allocas through phi instructions, so it did not consider
; alloca and alloca2 to be live at the same time. As a result it was using
; the same stack slot for both allocas. To ensure this bug isn't present, we
; check that there are 64 bytes allocated for the unsafe stack which is enough
; space for both allocas.
; CHECK-LABEL: @stack_coloring_liveness_bug
define void @stack_coloring_liveness_bug(i32 %arg0) #0 {
entry:
; CHECK: %[[USP:.*]] = load i8*, i8** @__safestack_unsafe_stack_ptr
; CHECK-NEXT: getelementptr i8, i8* %[[USP]], i32 -64
%alloca = alloca [32 x i8], align 16
%alloca2 = alloca [32 x i8], align 16
%cond = icmp eq i32 %arg0, 0
br i1 %cond, label %if, label %else
if:
%alloca.if = bitcast [32 x i8]* %alloca to i8*
br label %end
else:
; CHECK: getelementptr i8, i8* %[[USP]], i32 -32
%alloca.else = bitcast [32 x i8]* %alloca to i8*
call void @llvm.lifetime.start.p0i8(i64 32, i8* nonnull %alloca.else)
call void @capture8(i8* %alloca.else)
call void @llvm.lifetime.end.p0i8(i64 32, i8* nonnull %alloca.else)
br label %end
end:
; CHECK: getelementptr i8, i8* %[[USP]], i32 -64
%alloca.end = phi i8* [ %alloca.if, %if], [%alloca.else, %else]
%alloca2.bitcast = bitcast [32 x i8]* %alloca2 to i8*
call void @llvm.lifetime.start.p0i8(i64 32, i8* nonnull %alloca2.bitcast)
call void @llvm.lifetime.start.p0i8(i64 32, i8* nonnull %alloca.end)
call void @capture2_8(i8* %alloca2.bitcast, i8* %alloca.end)
call void @llvm.lifetime.end.p0i8(i64 32, i8* nonnull %alloca2.bitcast)
call void @llvm.lifetime.end.p0i8(i64 32, i8* nonnull %alloca.end)
ret void
}
attributes #0 = { safestack }
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
declare void @capture8(i8*)
declare void @capture32(i32*)
declare void @capture64(i64*)
declare void @capture100x32([100 x i32]*)
declare void @capture2_8(i8*, i8*)