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[WebAssembly] Correctly consider signext/zext arg flags at function declaration (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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‎llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -839,9 +839,9 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
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unsigned Reg;
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if (Attrs.hasParamAttr(I, Attribute::SExt))
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if (Call->paramHasAttr(I, Attribute::SExt))
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Reg = getRegForSignedValue(V);
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else if (Attrs.hasParamAttr(I, Attribute::ZExt))
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else if (Call->paramHasAttr(I, Attribute::ZExt))
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Reg = getRegForUnsignedValue(V);
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else
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Reg = getRegForValue(V);

‎llvm/test/CodeGen/WebAssembly/signext-zeroext-callsite.ll

Lines changed: 186 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,186 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc < %s -O0 | FileCheck %s
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; RUN: llc -fast-isel=false < %s -O0 | FileCheck %s -check-prefixes NO-FAST-ISEL
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target triple = "wasm32-unknown-unknown"
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declare i32 @foo(i1 signext noundef, i32 noundef)
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; callsite_signext and callsite_nosignext must emit equivalent codes
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define i32 @callsite_nosignext() {
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; CHECK-LABEL: callsite_nosignext:
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; CHECK: .functype callsite_nosignext () -> (i32)
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; CHECK-NEXT: .local i32, i32, i32, i32, i32, i32
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; CHECK-NEXT: # %bb.0: # %start
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 0
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; CHECK-NEXT: i32.const 0
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; CHECK-NEXT: local.set 1
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; CHECK-NEXT: i32.const 31
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; CHECK-NEXT: local.set 2
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; CHECK-NEXT: local.get 0
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.shl
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; CHECK-NEXT: local.set 3
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; CHECK-NEXT: local.get 3
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.shr_s
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; CHECK-NEXT: local.set 4
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; CHECK-NEXT: local.get 4
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; CHECK-NEXT: local.get 1
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; CHECK-NEXT: call foo
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; CHECK-NEXT: local.set 5
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; CHECK-NEXT: local.get 5
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; CHECK-NEXT: return
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;
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; NO-FAST-ISEL-LABEL: callsite_nosignext:
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; NO-FAST-ISEL: .functype callsite_nosignext () -> (i32)
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; NO-FAST-ISEL-NEXT: .local i32, i32, i32
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; NO-FAST-ISEL-NEXT: # %bb.0: # %start
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; NO-FAST-ISEL-NEXT: i32.const 0
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; NO-FAST-ISEL-NEXT: local.set 0
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; NO-FAST-ISEL-NEXT: i32.const -1
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; NO-FAST-ISEL-NEXT: local.set 1
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; NO-FAST-ISEL-NEXT: local.get 1
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; NO-FAST-ISEL-NEXT: local.get 0
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; NO-FAST-ISEL-NEXT: call foo
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; NO-FAST-ISEL-NEXT: local.set 2
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; NO-FAST-ISEL-NEXT: local.get 2
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; NO-FAST-ISEL-NEXT: return
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start:
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%0 = call i32 @foo(i1 1, i32 0)
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ret i32 %0
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}
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define i32 @callsite_signext() {
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; CHECK-LABEL: callsite_signext:
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; CHECK: .functype callsite_signext () -> (i32)
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; CHECK-NEXT: .local i32, i32, i32, i32, i32, i32
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; CHECK-NEXT: # %bb.0: # %start
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 0
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; CHECK-NEXT: i32.const 0
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; CHECK-NEXT: local.set 1
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; CHECK-NEXT: i32.const 31
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; CHECK-NEXT: local.set 2
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; CHECK-NEXT: local.get 0
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.shl
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; CHECK-NEXT: local.set 3
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; CHECK-NEXT: local.get 3
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.shr_s
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; CHECK-NEXT: local.set 4
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; CHECK-NEXT: local.get 4
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; CHECK-NEXT: local.get 1
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; CHECK-NEXT: call foo
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; CHECK-NEXT: local.set 5
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; CHECK-NEXT: local.get 5
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; CHECK-NEXT: return
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;
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; NO-FAST-ISEL-LABEL: callsite_signext:
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; NO-FAST-ISEL: .functype callsite_signext () -> (i32)
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; NO-FAST-ISEL-NEXT: .local i32, i32, i32
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; NO-FAST-ISEL-NEXT: # %bb.0: # %start
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; NO-FAST-ISEL-NEXT: i32.const 0
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; NO-FAST-ISEL-NEXT: local.set 0
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; NO-FAST-ISEL-NEXT: i32.const -1
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; NO-FAST-ISEL-NEXT: local.set 1
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; NO-FAST-ISEL-NEXT: local.get 1
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; NO-FAST-ISEL-NEXT: local.get 0
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; NO-FAST-ISEL-NEXT: call foo
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; NO-FAST-ISEL-NEXT: local.set 2
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; NO-FAST-ISEL-NEXT: local.get 2
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; NO-FAST-ISEL-NEXT: return
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start:
98+
%0 = call i32 @foo(i1 signext 1, i32 0)
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ret i32 %0
100+
}
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declare i32 @foo2(i1 zeroext noundef, i32 noundef)
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; callsite_zeroext and callsite_nozeroext must emit equivalent codes
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define i32 @callsite_nozeroext() {
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; CHECK-LABEL: callsite_nozeroext:
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; CHECK: .functype callsite_nozeroext () -> (i32)
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; CHECK-NEXT: .local i32, i32, i32, i32, i32
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; CHECK-NEXT: # %bb.0: # %start
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 0
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; CHECK-NEXT: i32.const 0
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; CHECK-NEXT: local.set 1
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 2
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; CHECK-NEXT: local.get 0
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.and
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; CHECK-NEXT: local.set 3
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; CHECK-NEXT: local.get 3
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; CHECK-NEXT: local.get 1
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; CHECK-NEXT: call foo2
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; CHECK-NEXT: local.set 4
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; CHECK-NEXT: local.get 4
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; CHECK-NEXT: return
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;
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; NO-FAST-ISEL-LABEL: callsite_nozeroext:
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; NO-FAST-ISEL: .functype callsite_nozeroext () -> (i32)
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; NO-FAST-ISEL-NEXT: .local i32, i32, i32
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; NO-FAST-ISEL-NEXT: # %bb.0: # %start
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; NO-FAST-ISEL-NEXT: i32.const 0
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; NO-FAST-ISEL-NEXT: local.set 0
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; NO-FAST-ISEL-NEXT: i32.const 1
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; NO-FAST-ISEL-NEXT: local.set 1
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; NO-FAST-ISEL-NEXT: local.get 1
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; NO-FAST-ISEL-NEXT: local.get 0
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; NO-FAST-ISEL-NEXT: call foo2
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; NO-FAST-ISEL-NEXT: local.set 2
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; NO-FAST-ISEL-NEXT: local.get 2
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; NO-FAST-ISEL-NEXT: return
142+
start:
143+
%0 = call i32 @foo2(i1 1, i32 0)
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ret i32 %0
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}
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define i32 @callsite_zeroext() {
148+
; CHECK-LABEL: callsite_zeroext:
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; CHECK: .functype callsite_zeroext () -> (i32)
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; CHECK-NEXT: .local i32, i32, i32, i32, i32
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; CHECK-NEXT: # %bb.0: # %start
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 0
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; CHECK-NEXT: i32.const 0
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; CHECK-NEXT: local.set 1
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; CHECK-NEXT: i32.const 1
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; CHECK-NEXT: local.set 2
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; CHECK-NEXT: local.get 0
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; CHECK-NEXT: local.get 2
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; CHECK-NEXT: i32.and
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; CHECK-NEXT: local.set 3
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; CHECK-NEXT: local.get 3
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; CHECK-NEXT: local.get 1
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; CHECK-NEXT: call foo2
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; CHECK-NEXT: local.set 4
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; CHECK-NEXT: local.get 4
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; CHECK-NEXT: return
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;
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; NO-FAST-ISEL-LABEL: callsite_zeroext:
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; NO-FAST-ISEL: .functype callsite_zeroext () -> (i32)
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; NO-FAST-ISEL-NEXT: .local i32, i32, i32
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; NO-FAST-ISEL-NEXT: # %bb.0: # %start
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; NO-FAST-ISEL-NEXT: i32.const 0
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; NO-FAST-ISEL-NEXT: local.set 0
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; NO-FAST-ISEL-NEXT: i32.const 1
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; NO-FAST-ISEL-NEXT: local.set 1
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; NO-FAST-ISEL-NEXT: local.get 1
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; NO-FAST-ISEL-NEXT: local.get 0
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; NO-FAST-ISEL-NEXT: call foo2
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; NO-FAST-ISEL-NEXT: local.set 2
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; NO-FAST-ISEL-NEXT: local.get 2
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; NO-FAST-ISEL-NEXT: return
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start:
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%0 = call i32 @foo2(i1 zeroext 1, i32 0)
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ret i32 %0
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}

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