[X86] Avoid clobbering ESP/RSP in the epilogue.

rnk · rnk · commit fe5e5dcab0c0 · 2019-01-15T01:24:18.000Z
Summary: In r345197 ESP and RSP were added to GR32_TC/GR64_TC, allowing them to be used for tail calls, but this also caused `findDeadCallerSavedReg` to think they were acceptable targets for clobbering. Filter them out. Fixes PR40289. Patch by Geoffry Song! Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D56617 llvm-svn: 351146
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -185,7 +185,8 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
     }
 
     for (auto CS : AvailableRegs)
-      if (!Uses.count(CS) && CS != X86::RIP)
+      if (!Uses.count(CS) && CS != X86::RIP && CS != X86::RSP &&
+          CS != X86::ESP)
         return CS;
   }
   }
diff --git a/llvm/test/CodeGen/X86/pr40289-64bit.ll b/llvm/test/CodeGen/X86/pr40289-64bit.ll
@@ -0,0 +1,10 @@
+; RUN: llc < %s -mtriple=x86_64-pc-windows-msvc | FileCheck %s
+
+define cc 92 < 9 x i64 > @clobber() {
+  %1 = alloca i64
+  %2 = load volatile i64, i64* %1
+  ret < 9 x i64 > undef
+  ; CHECK-LABEL: clobber:
+  ; CHECK-NOT: popq %rsp
+  ; CHECK: addq $8, %rsp
+}
diff --git a/llvm/test/CodeGen/X86/pr40289.ll b/llvm/test/CodeGen/X86/pr40289.ll
@@ -0,0 +1,10 @@
+; RUN: llc < %s -mtriple=i686-pc-windows-msvc | FileCheck %s
+
+define < 3 x i32 > @clobber() {
+  %1 = alloca i32
+  %2 = load volatile i32, i32* %1
+  ret < 3 x i32 > undef
+  ; CHECK-LABEL: clobber:
+  ; CHECK-NOT: popl %esp
+  ; CHECK: addl $4, %esp
+}

Original file line number	Diff line number	Diff line change
`@@ -185,7 +185,8 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,`
`185`	`185`	`}`
`186`	`186`
`187`	`187`	`for (auto CS : AvailableRegs)`
`188`		`- if (!Uses.count(CS) && CS != X86::RIP)`
	`188`	`+ if (!Uses.count(CS) && CS != X86::RIP && CS != X86::RSP &&`
	`189`	`+ CS != X86::ESP)`
`189`	`190`	`return CS;`
`190`	`191`	`}`
`191`	`192`	`}`