[llvm] 0fca651 - [WebAssembly] Don't fold frame offset for global addresses
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 3 14:57:03 PST 2020
Author: Julien Jorge
Date: 2020-11-03T14:56:25-08:00
New Revision: 0fca6517118d435f9c2d7afe6135fd5f357509b5
URL: https://github.com/llvm/llvm-project/commit/0fca6517118d435f9c2d7afe6135fd5f357509b5
DIFF: https://github.com/llvm/llvm-project/commit/0fca6517118d435f9c2d7afe6135fd5f357509b5.diff
LOG: [WebAssembly] Don't fold frame offset for global addresses
When machine instructions are in the form of
```
%0 = CONST_I32 @str
%1 = ADD_I32 %stack.0, %0
%2 = LOAD 0, 0, %1
```
In the `ADD_I32` instruction, it is possible to fold it if `%0` is a
`CONST_I32` from an immediate number. But in this case it is a global
address, so we shouldn't do that. But we haven't checked if the operand
of `ADD` is an immediate so far. This fixes the problem. (The case
applies the same for `ADD_I64` and `CONST_I64` instructions.)
Fixes https://bugs.llvm.org/show_bug.cgi?id=47944.
Patch by Julien Jorge (jjorge at quarkslab.com)
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D90577
Added:
Modified:
llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
llvm/test/CodeGen/WebAssembly/userstack.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
index 130589c9df8c..6b6394a58339 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
@@ -101,10 +101,12 @@ void WebAssemblyRegisterInfo::eliminateFrameIndex(
WebAssemblyFrameLowering::getOpcConst(MF) &&
MRI.hasOneNonDBGUse(Def->getOperand(0).getReg())) {
MachineOperand &ImmMO = Def->getOperand(1);
- ImmMO.setImm(ImmMO.getImm() + uint32_t(FrameOffset));
- MI.getOperand(FIOperandNum)
- .ChangeToRegister(FrameRegister, /*isDef=*/false);
- return;
+ if (ImmMO.isImm()) {
+ ImmMO.setImm(ImmMO.getImm() + uint32_t(FrameOffset));
+ MI.getOperand(FIOperandNum)
+ .ChangeToRegister(FrameRegister, /*isDef=*/false);
+ return;
+ }
}
}
}
diff --git a/llvm/test/CodeGen/WebAssembly/userstack.ll b/llvm/test/CodeGen/WebAssembly/userstack.ll
index dec202ea6af9..3d0e0d8c86a0 100644
--- a/llvm/test/CodeGen/WebAssembly/userstack.ll
+++ b/llvm/test/CodeGen/WebAssembly/userstack.ll
@@ -328,6 +328,22 @@ define void @inline_asm() {
ret void
}
+; We optimize the format of "frame offset + operand" by folding it, but this is
+; only possible when that operand is an immediate. In this example it is a
+; global address, so we should not fold it.
+; CHECK-LABEL: frame_offset_with_global_address
+; CHECK: i[[PTR]].const ${{.*}}=, str
+ at str = local_unnamed_addr global [3 x i8] c"abc", align 16
+define i8 @frame_offset_with_global_address() {
+ %1 = alloca i8, align 4
+ %2 = ptrtoint i8* %1 to i32
+ ;; Here @str is a global address and not an immediate, so cannot be folded
+ %3 = getelementptr [3 x i8], [3 x i8]* @str, i32 0, i32 %2
+ %4 = load i8, i8* %3, align 8
+ %5 = and i8 %4, 67
+ ret i8 %5
+}
+
; CHECK: .globaltype __stack_pointer, i[[PTR]]{{$}}
; TODO: test over-aligned alloca
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