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[WebAssembly] Correctly consider signext/zext arg flags at function d…
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…eclaration (llvm#77281)

This patch fixes WebAssembly's FastISel pass to correctly consider
signext/zeroext parameter flags at function declaration.
Previously, the flags at call sites were only considered during code
generation, which caused an interesting bug report llvm#63388 .
This is problematic especially because in WebAssembly's ABI, either
signext or zeroext can be tagged to a function argument, and it must be
correctly reflected in the generated code. Unit test
https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/WebAssembly/signext-zeroext.ll
shows that `i8 zeroext %t` and `i8 signext %t`'s code gen are different.
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@aqjune
aqjune authored Jan 10, 2024
1 parent c2b57a0 commit 7388b74
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4 changes: 2 additions & 2 deletions llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -839,9 +839,9 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {

unsigned Reg;

if (Attrs.hasParamAttr(I, Attribute::SExt))
if (Call->paramHasAttr(I, Attribute::SExt))
Reg = getRegForSignedValue(V);
else if (Attrs.hasParamAttr(I, Attribute::ZExt))
else if (Call->paramHasAttr(I, Attribute::ZExt))
Reg = getRegForUnsignedValue(V);
else
Reg = getRegForValue(V);
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186 changes: 186 additions & 0 deletions llvm/test/CodeGen/WebAssembly/signext-zeroext-callsite.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,186 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -O0 | FileCheck %s
; RUN: llc -fast-isel=false < %s -O0 | FileCheck %s -check-prefixes NO-FAST-ISEL

target triple = "wasm32-unknown-unknown"


declare i32 @foo(i1 signext noundef, i32 noundef)

; callsite_signext and callsite_nosignext must emit equivalent codes

define i32 @callsite_nosignext() {
; CHECK-LABEL: callsite_nosignext:
; CHECK: .functype callsite_nosignext () -> (i32)
; CHECK-NEXT: .local i32, i32, i32, i32, i32, i32
; CHECK-NEXT: # %bb.0: # %start
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 0
; CHECK-NEXT: i32.const 0
; CHECK-NEXT: local.set 1
; CHECK-NEXT: i32.const 31
; CHECK-NEXT: local.set 2
; CHECK-NEXT: local.get 0
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.shl
; CHECK-NEXT: local.set 3
; CHECK-NEXT: local.get 3
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.shr_s
; CHECK-NEXT: local.set 4
; CHECK-NEXT: local.get 4
; CHECK-NEXT: local.get 1
; CHECK-NEXT: call foo
; CHECK-NEXT: local.set 5
; CHECK-NEXT: local.get 5
; CHECK-NEXT: return
;
; NO-FAST-ISEL-LABEL: callsite_nosignext:
; NO-FAST-ISEL: .functype callsite_nosignext () -> (i32)
; NO-FAST-ISEL-NEXT: .local i32, i32, i32
; NO-FAST-ISEL-NEXT: # %bb.0: # %start
; NO-FAST-ISEL-NEXT: i32.const 0
; NO-FAST-ISEL-NEXT: local.set 0
; NO-FAST-ISEL-NEXT: i32.const -1
; NO-FAST-ISEL-NEXT: local.set 1
; NO-FAST-ISEL-NEXT: local.get 1
; NO-FAST-ISEL-NEXT: local.get 0
; NO-FAST-ISEL-NEXT: call foo
; NO-FAST-ISEL-NEXT: local.set 2
; NO-FAST-ISEL-NEXT: local.get 2
; NO-FAST-ISEL-NEXT: return
start:
%0 = call i32 @foo(i1 1, i32 0)
ret i32 %0
}

define i32 @callsite_signext() {
; CHECK-LABEL: callsite_signext:
; CHECK: .functype callsite_signext () -> (i32)
; CHECK-NEXT: .local i32, i32, i32, i32, i32, i32
; CHECK-NEXT: # %bb.0: # %start
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 0
; CHECK-NEXT: i32.const 0
; CHECK-NEXT: local.set 1
; CHECK-NEXT: i32.const 31
; CHECK-NEXT: local.set 2
; CHECK-NEXT: local.get 0
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.shl
; CHECK-NEXT: local.set 3
; CHECK-NEXT: local.get 3
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.shr_s
; CHECK-NEXT: local.set 4
; CHECK-NEXT: local.get 4
; CHECK-NEXT: local.get 1
; CHECK-NEXT: call foo
; CHECK-NEXT: local.set 5
; CHECK-NEXT: local.get 5
; CHECK-NEXT: return
;
; NO-FAST-ISEL-LABEL: callsite_signext:
; NO-FAST-ISEL: .functype callsite_signext () -> (i32)
; NO-FAST-ISEL-NEXT: .local i32, i32, i32
; NO-FAST-ISEL-NEXT: # %bb.0: # %start
; NO-FAST-ISEL-NEXT: i32.const 0
; NO-FAST-ISEL-NEXT: local.set 0
; NO-FAST-ISEL-NEXT: i32.const -1
; NO-FAST-ISEL-NEXT: local.set 1
; NO-FAST-ISEL-NEXT: local.get 1
; NO-FAST-ISEL-NEXT: local.get 0
; NO-FAST-ISEL-NEXT: call foo
; NO-FAST-ISEL-NEXT: local.set 2
; NO-FAST-ISEL-NEXT: local.get 2
; NO-FAST-ISEL-NEXT: return
start:
%0 = call i32 @foo(i1 signext 1, i32 0)
ret i32 %0
}

declare i32 @foo2(i1 zeroext noundef, i32 noundef)

; callsite_zeroext and callsite_nozeroext must emit equivalent codes

define i32 @callsite_nozeroext() {
; CHECK-LABEL: callsite_nozeroext:
; CHECK: .functype callsite_nozeroext () -> (i32)
; CHECK-NEXT: .local i32, i32, i32, i32, i32
; CHECK-NEXT: # %bb.0: # %start
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 0
; CHECK-NEXT: i32.const 0
; CHECK-NEXT: local.set 1
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 2
; CHECK-NEXT: local.get 0
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.and
; CHECK-NEXT: local.set 3
; CHECK-NEXT: local.get 3
; CHECK-NEXT: local.get 1
; CHECK-NEXT: call foo2
; CHECK-NEXT: local.set 4
; CHECK-NEXT: local.get 4
; CHECK-NEXT: return
;
; NO-FAST-ISEL-LABEL: callsite_nozeroext:
; NO-FAST-ISEL: .functype callsite_nozeroext () -> (i32)
; NO-FAST-ISEL-NEXT: .local i32, i32, i32
; NO-FAST-ISEL-NEXT: # %bb.0: # %start
; NO-FAST-ISEL-NEXT: i32.const 0
; NO-FAST-ISEL-NEXT: local.set 0
; NO-FAST-ISEL-NEXT: i32.const 1
; NO-FAST-ISEL-NEXT: local.set 1
; NO-FAST-ISEL-NEXT: local.get 1
; NO-FAST-ISEL-NEXT: local.get 0
; NO-FAST-ISEL-NEXT: call foo2
; NO-FAST-ISEL-NEXT: local.set 2
; NO-FAST-ISEL-NEXT: local.get 2
; NO-FAST-ISEL-NEXT: return
start:
%0 = call i32 @foo2(i1 1, i32 0)
ret i32 %0
}

define i32 @callsite_zeroext() {
; CHECK-LABEL: callsite_zeroext:
; CHECK: .functype callsite_zeroext () -> (i32)
; CHECK-NEXT: .local i32, i32, i32, i32, i32
; CHECK-NEXT: # %bb.0: # %start
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 0
; CHECK-NEXT: i32.const 0
; CHECK-NEXT: local.set 1
; CHECK-NEXT: i32.const 1
; CHECK-NEXT: local.set 2
; CHECK-NEXT: local.get 0
; CHECK-NEXT: local.get 2
; CHECK-NEXT: i32.and
; CHECK-NEXT: local.set 3
; CHECK-NEXT: local.get 3
; CHECK-NEXT: local.get 1
; CHECK-NEXT: call foo2
; CHECK-NEXT: local.set 4
; CHECK-NEXT: local.get 4
; CHECK-NEXT: return
;
; NO-FAST-ISEL-LABEL: callsite_zeroext:
; NO-FAST-ISEL: .functype callsite_zeroext () -> (i32)
; NO-FAST-ISEL-NEXT: .local i32, i32, i32
; NO-FAST-ISEL-NEXT: # %bb.0: # %start
; NO-FAST-ISEL-NEXT: i32.const 0
; NO-FAST-ISEL-NEXT: local.set 0
; NO-FAST-ISEL-NEXT: i32.const 1
; NO-FAST-ISEL-NEXT: local.set 1
; NO-FAST-ISEL-NEXT: local.get 1
; NO-FAST-ISEL-NEXT: local.get 0
; NO-FAST-ISEL-NEXT: call foo2
; NO-FAST-ISEL-NEXT: local.set 2
; NO-FAST-ISEL-NEXT: local.get 2
; NO-FAST-ISEL-NEXT: return
start:
%0 = call i32 @foo2(i1 zeroext 1, i32 0)
ret i32 %0
}

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