Commit 45555c38 authored by Nikita Popov's avatar Nikita Popov
Browse files

[InstSimplify] Simplify calls with "returned" attribute 

If a call argument has the "returned" attribute, we can simplify
the call to the value of that argument. The "-inst-simplify" pass
already handled this for the constant integer argument case via
known bits, which is invoked in SimplifyInstruction. However,
non-constant (or non-int) arguments are not handled at all right now.

This addresses one of the regressions from D75801.

Differential Revision: https://reviews.llvm.org/D75815
parent a8f76e99

llvm/lib/Analysis/InstructionSimplify.cpp

+3 −0
Original line number Diff line number Diff line
@@ -5348,6 +5348,9 @@ Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) { 
    if (Value *Ret = simplifyIntrinsic(Call, Q))

      return Ret;



  if (Value *ReturnedArg = Call->getReturnedArgOperand())

    return ReturnedArg;



  if (!canConstantFoldCallTo(Call, F))

    return nullptr;

llvm/test/Analysis/ValueTracking/known-nonnull-at.ll

+1 −1
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ define i1 @nonnullReturnTest(i8* nonnull %x) { 
define i1 @unknownReturnTest(i8* %x) {

; CHECK-LABEL: @unknownReturnTest(

; CHECK-NEXT:    [[X2:%.*]] = call i8* @returningPtr(i8* [[X:%.*]])

; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i8* [[X2]], null

; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i8* [[X]], null

; CHECK-NEXT:    ret i1 [[NULL_CHECK]]

;

  %x2 = call i8* @returningPtr(i8* %x)

llvm/test/Transforms/InstCombine/align-attr.ll

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ define i32 @foo2(i32* align 32 %a) #0 { 
; CHECK-LABEL: @foo2(

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[V:%.*]] = call i32* @func1(i32* [[A:%.*]])

; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[V]], align 32

; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[A]], align 32

; CHECK-NEXT:    ret i32 [[TMP0]]

;

entry:

llvm/test/Transforms/InstCombine/expensive-combines.ll

+1 −1
Original line number Diff line number Diff line
@@ -16,7 +16,7 @@ define void @test() { 
;

; EXPENSIVE-OFF-LABEL: @test(

; EXPENSIVE-OFF-NEXT:    [[CALL:%.*]] = call i32 @passthru(i32 0)

; EXPENSIVE-OFF-NEXT:    call void @sink(i32 [[CALL]])

; EXPENSIVE-OFF-NEXT:    call void @sink(i32 0)

; EXPENSIVE-OFF-NEXT:    ret void

;

  %call = call i32 @passthru(i32 0)

llvm/test/Transforms/InstCombine/fortify-folding.ll

+2 −2
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ define i32 @test_not_sprintf() { 
define i8* @test_strcat() {

; CHECK-LABEL: @test_strcat(

; CHECK-NEXT:    [[STRCAT:%.*]] = call i8* @strcat(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0))

; CHECK-NEXT:    ret i8* [[STRCAT]]

; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0)

;

  %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0

  %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0
@@ -126,7 +126,7 @@ define i64 @test_not_strlcat() { 
define i8* @test_strncat() {

; CHECK-LABEL: @test_strncat(

; CHECK-NEXT:    [[STRNCAT:%.*]] = call i8* @strncat(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0), i64 22)

; CHECK-NEXT:    ret i8* [[STRNCAT]]

; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0)

;

  %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0

  %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0