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[PowerPC] Do not produce invalid CTR loop with an FRem

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An FRem instruction inside a loop should prevent the loop from being converted
into a CTR loop since this is not an operation that is legal on any PPC
subtarget. This will always be a call to a library function which means the
loop will be invalid if this instruction is in the body.

Fixes PR36292.

llvm-svn: 325739
This commit is contained in:
Nemanja Ivanovic 2018-02-22 03:02:41 +00:00
parent ed7d7cb126
commit 237f644f7b
2 changed files with 50 additions and 1 deletions
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5
lib/Target/PowerPC/PPCCTRLoops.cpp
View File

@ -455,13 +455,16 @@ bool PPCCTRLoops::mightUseCTR(BasicBlock *BB) {
return true;
}
// FREM is always a call.
if (J->getOpcode() == Instruction::FRem)
return true;
if (STI->useSoftFloat()) {
switch(J->getOpcode()) {
case Instruction::FAdd:
case Instruction::FSub:
case Instruction::FMul:
case Instruction::FDiv:
case Instruction::FRem:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:

46
test/CodeGen/PowerPC/pr36292.ll Normal file
View File

@ -0,0 +1,46 @@
; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-unknown < %s | \
; RUN: FileCheck %s --implicit-check-not=mtctr --implicit-check-not=bdnz
$test = comdat any
; No CTR loop due to frem (since it is always a call).
define void @test() #0 comdat {
; CHECK-LABEL: test:
; CHECK: ld 29, 0(3)
; CHECK: ld 30, 40(1)
; CHECK: xxlxor 31, 31, 31
; CHECK: cmpld 30, 29
; CHECK-NEXT: bge- 0, .LBB0_2
; CHECK-NEXT: .p2align 5
; CHECK-NEXT: .LBB0_1: # %bounds.ok
; CHECK: fmr 1, 31
; CHECK-NEXT: lfsx 2, 0, 3
; CHECK-NEXT: bl fmodf
; CHECK-NEXT: nop
; CHECK-NEXT: addi 30, 30, 1
; CHECK-NEXT: stfsx 1, 0, 3
; CHECK-NEXT: cmpld 30, 29
; CHECK-NEXT: blt+ 0, .LBB0_1
; CHECK-NEXT: .LBB0_2: # %bounds.fail
; CHECK-NEXT: std 30, 40(1)
%pos = alloca i64, align 8
br label %forcond
forcond: ; preds = %bounds.ok, %0
%1 = load i64, i64* %pos
%.len1 = load i64, i64* undef
%bounds.cmp = icmp ult i64 %1, %.len1
br i1 %bounds.cmp, label %bounds.ok, label %bounds.fail
bounds.ok: ; preds = %forcond
%2 = load float, float* undef
%3 = frem float 0.000000e+00, %2
store float %3, float* undef
%4 = load i64, i64* %pos
%5 = add i64 %4, 1
store i64 %5, i64* %pos
br label %forcond
bounds.fail: ; preds = %forcond
unreachable
}