From 5c6cb813b6a2d36713a3e67a2aa40e220e27ede9 Mon Sep 17 00:00:00 2001 From: Bill Schmidt Date: Tue, 21 Oct 2014 13:02:37 +0000 Subject: [PATCH] [PowerPC] Avoid VSX FMA mutate when killed product reg = addend reg With VSX enabled, test/CodeGen/PowerPC/recipest.ll exposes a bug in the FMA mutation pass. If we have a situation where a killed product register is the same register as the FMA target, such as: %vreg5 = XSNMSUBADP %vreg5, %vreg11, %vreg5, %RM; VSFRC:%vreg5 F8RC:%vreg11 then the substitution makes no sense. We end up getting a crash when we try to extend the interval associated with the killed product register, as there is already a live range for %vreg5 there. This patch just disables the mutation under those circumstances. Since recipest.ll generates different code with VMX enabled, I've modified that test to use -mattr=-vsx. I've borrowed the code from that test that exposed the bug and placed it in fma-mutate.ll, where it tests several mutation opportunities including the "bad" one. llvm-svn: 220290 --- llvm/lib/Target/PowerPC/PPCInstrInfo.cpp | 6 ++++++ llvm/test/CodeGen/PowerPC/fma-mutate.ll | 21 +++++++++++++++++++++ llvm/test/CodeGen/PowerPC/recipest.ll | 4 ++-- 3 files changed, 29 insertions(+), 2 deletions(-) create mode 100644 llvm/test/CodeGen/PowerPC/fma-mutate.ll diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp index ff2633eac3f8..daf8790fefcc 100644 --- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp +++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp @@ -1754,6 +1754,12 @@ protected: unsigned OldFMAReg = MI->getOperand(0).getReg(); + // The transformation doesn't work well with things like: + // %vreg5 = A-form-op %vreg5, %vreg11, %vreg5; + // so leave such things alone. + if (OldFMAReg == KilledProdReg) + continue; + assert(OldFMAReg == AddendMI->getOperand(0).getReg() && "Addend copy not tied to old FMA output!"); diff --git a/llvm/test/CodeGen/PowerPC/fma-mutate.ll b/llvm/test/CodeGen/PowerPC/fma-mutate.ll new file mode 100644 index 000000000000..1a391f4c2305 --- /dev/null +++ b/llvm/test/CodeGen/PowerPC/fma-mutate.ll @@ -0,0 +1,21 @@ +; Test several VSX FMA mutation opportunities. The first one isn't a +; reasonable transformation because the killed product register is the +; same as the FMA target register. The second one is legal. The third +; one doesn't fit the feeding-copy pattern. + +; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -enable-unsafe-fp-math -mattr=+vsx | FileCheck %s +target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64" +target triple = "powerpc64-unknown-linux-gnu" + +declare double @llvm.sqrt.f64(double) + +define double @foo3(double %a) nounwind { + %r = call double @llvm.sqrt.f64(double %a) + ret double %r + +; CHECK: @foo3 +; CHECK: xsnmsubadp [[REG:[0-9]+]], {{[0-9]+}}, [[REG]] +; CHECK: xsmaddmdp +; CHECK: xsmaddadp +} + diff --git a/llvm/test/CodeGen/PowerPC/recipest.ll b/llvm/test/CodeGen/PowerPC/recipest.ll index 2f6a3eca4882..cd77548b281b 100644 --- a/llvm/test/CodeGen/PowerPC/recipest.ll +++ b/llvm/test/CodeGen/PowerPC/recipest.ll @@ -1,5 +1,5 @@ -; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -enable-unsafe-fp-math | FileCheck %s -; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | FileCheck -check-prefix=CHECK-SAFE %s +; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -enable-unsafe-fp-math -mattr=-vsx | FileCheck %s +; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -mattr=-vsx | FileCheck -check-prefix=CHECK-SAFE %s target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64" target triple = "powerpc64-unknown-linux-gnu"