[X86] Improve test instruction shrinking when the sign flag is used and the output of the and is truncated

Currently we skip looking through truncates if the sign flag is used. But that's overly restrictive.

It's safe to look through the truncate as long as we ensure one of the 3 things when we shrink. Either the MSB of the mask at the shrunken size isn't set. If the mask bit is set then either the shrunk size needs to be equal to the compare size or the sign flag needs to be unused.

There are still missed opportunities to shrink a load and fold it in here. This will be fixed in a future patch.

Differential Revision: https://reviews.llvm.org/D52669

2 files changed, 20 insertions, 36 deletions

diff --git a/llvm/test/CodeGen/X86/2010-08-04-MaskedSignedCompare.ll b/llvm/test/CodeGen/X86/2010-08-04-MaskedSignedCompare.ll
index 9bbd86ca646..4f6f0c9201b 100644
--- a/llvm/test/CodeGen/X86/2010-08-04-MaskedSignedCompare.ll
+++ b/llvm/test/CodeGen/X86/2010-08-04-MaskedSignedCompare.ll
@@ -12,8 +12,7 @@ define i32 @main() nounwind {
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    cmpq {{.*}}(%rip), %rax
 ; CHECK-NEXT:    sbbl %eax, %eax
-; CHECK-NEXT:    andl $150, %eax
-; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    testb $-106, %al
 ; CHECK-NEXT:    jle .LBB0_1
 ; CHECK-NEXT:  # %bb.2: # %if.then
 ; CHECK-NEXT:    movl $1, {{.*}}(%rip)
diff --git a/llvm/test/CodeGen/X86/test-shrink.ll b/llvm/test/CodeGen/X86/test-shrink.ll
index c83e7fa8322..e0351452bd8 100644
--- a/llvm/test/CodeGen/X86/test-shrink.ll
+++ b/llvm/test/CodeGen/X86/test-shrink.ll
@@ -578,8 +578,7 @@ no:
 define void @and16_trunc_8_sign(i16 %x) nounwind {
 ; CHECK-LINUX64-LABEL: and16_trunc_8_sign:
 ; CHECK-LINUX64:       # %bb.0:
-; CHECK-LINUX64-NEXT:    andl $128, %edi
-; CHECK-LINUX64-NEXT:    testb %dil, %dil
+; CHECK-LINUX64-NEXT:    testb $-128, %dil
 ; CHECK-LINUX64-NEXT:    jg .LBB13_2
 ; CHECK-LINUX64-NEXT:  # %bb.1: # %yes
 ; CHECK-LINUX64-NEXT:    pushq %rax
@@ -592,8 +591,7 @@ define void @and16_trunc_8_sign(i16 %x) nounwind {
 ; CHECK-WIN32-64:       # %bb.0:
 ; CHECK-WIN32-64-NEXT:    subq $40, %rsp
 ; CHECK-WIN32-64-NEXT:    # kill: def $cx killed $cx def $ecx
-; CHECK-WIN32-64-NEXT:    andl $128, %ecx
-; CHECK-WIN32-64-NEXT:    testb %cl, %cl
+; CHECK-WIN32-64-NEXT:    testb $-128, %cl
 ; CHECK-WIN32-64-NEXT:    jg .LBB13_2
 ; CHECK-WIN32-64-NEXT:  # %bb.1: # %yes
 ; CHECK-WIN32-64-NEXT:    callq bar
@@ -604,8 +602,7 @@ define void @and16_trunc_8_sign(i16 %x) nounwind {
 ; CHECK-X86-LABEL: and16_trunc_8_sign:
 ; CHECK-X86:       # %bb.0:
 ; CHECK-X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
-; CHECK-X86-NEXT:    andl $128, %eax
-; CHECK-X86-NEXT:    testb %al, %al
+; CHECK-X86-NEXT:    testb $-128, %al
 ; CHECK-X86-NEXT:    jg .LBB13_2
 ; CHECK-X86-NEXT:  # %bb.1: # %yes
 ; CHECK-X86-NEXT:    calll bar
@@ -626,8 +623,7 @@ no:
 define void @and32_trunc_8_sign(i32 %x) nounwind {
 ; CHECK-LINUX64-LABEL: and32_trunc_8_sign:
 ; CHECK-LINUX64:       # %bb.0:
-; CHECK-LINUX64-NEXT:    andl $128, %edi
-; CHECK-LINUX64-NEXT:    testb %dil, %dil
+; CHECK-LINUX64-NEXT:    testb $-128, %dil
 ; CHECK-LINUX64-NEXT:    jg .LBB14_2
 ; CHECK-LINUX64-NEXT:  # %bb.1: # %yes
 ; CHECK-LINUX64-NEXT:    pushq %rax
@@ -639,8 +635,7 @@ define void @and32_trunc_8_sign(i32 %x) nounwind {
 ; CHECK-WIN32-64-LABEL: and32_trunc_8_sign:
 ; CHECK-WIN32-64:       # %bb.0:
 ; CHECK-WIN32-64-NEXT:    subq $40, %rsp
-; CHECK-WIN32-64-NEXT:    andl $128, %ecx
-; CHECK-WIN32-64-NEXT:    testb %cl, %cl
+; CHECK-WIN32-64-NEXT:    testb $-128, %cl
 ; CHECK-WIN32-64-NEXT:    jg .LBB14_2
 ; CHECK-WIN32-64-NEXT:  # %bb.1: # %yes
 ; CHECK-WIN32-64-NEXT:    callq bar
@@ -650,9 +645,8 @@ define void @and32_trunc_8_sign(i32 %x) nounwind {
 ;
 ; CHECK-X86-LABEL: and32_trunc_8_sign:
 ; CHECK-X86:       # %bb.0:
-; CHECK-X86-NEXT:    movl $128, %eax
-; CHECK-X86-NEXT:    andl {{[0-9]+}}(%esp), %eax
-; CHECK-X86-NEXT:    testb %al, %al
+; CHECK-X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-X86-NEXT:    testb $-128, %al
 ; CHECK-X86-NEXT:    jg .LBB14_2
 ; CHECK-X86-NEXT:  # %bb.1: # %yes
 ; CHECK-X86-NEXT:    calll bar
@@ -673,8 +667,7 @@ no:
 define void @and64_trunc_8_sign(i64 %x) nounwind {
 ; CHECK-LINUX64-LABEL: and64_trunc_8_sign:
 ; CHECK-LINUX64:       # %bb.0:
-; CHECK-LINUX64-NEXT:    andl $128, %edi
-; CHECK-LINUX64-NEXT:    testb %dil, %dil
+; CHECK-LINUX64-NEXT:    testb $-128, %dil
 ; CHECK-LINUX64-NEXT:    jg .LBB15_2
 ; CHECK-LINUX64-NEXT:  # %bb.1: # %yes
 ; CHECK-LINUX64-NEXT:    pushq %rax
@@ -686,8 +679,7 @@ define void @and64_trunc_8_sign(i64 %x) nounwind {
 ; CHECK-WIN32-64-LABEL: and64_trunc_8_sign:
 ; CHECK-WIN32-64:       # %bb.0:
 ; CHECK-WIN32-64-NEXT:    subq $40, %rsp
-; CHECK-WIN32-64-NEXT:    andl $128, %ecx
-; CHECK-WIN32-64-NEXT:    testb %cl, %cl
+; CHECK-WIN32-64-NEXT:    testb $-128, %cl
 ; CHECK-WIN32-64-NEXT:    jg .LBB15_2
 ; CHECK-WIN32-64-NEXT:  # %bb.1: # %yes
 ; CHECK-WIN32-64-NEXT:    callq bar
@@ -697,9 +689,8 @@ define void @and64_trunc_8_sign(i64 %x) nounwind {
 ;
 ; CHECK-X86-LABEL: and64_trunc_8_sign:
 ; CHECK-X86:       # %bb.0:
-; CHECK-X86-NEXT:    movl $128, %eax
-; CHECK-X86-NEXT:    andl {{[0-9]+}}(%esp), %eax
-; CHECK-X86-NEXT:    testb %al, %al
+; CHECK-X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-X86-NEXT:    testb $-128, %al
 ; CHECK-X86-NEXT:    jg .LBB15_2
 ; CHECK-X86-NEXT:  # %bb.1: # %yes
 ; CHECK-X86-NEXT:    calll bar
@@ -720,8 +711,7 @@ no:
 define void @and32_trunc_16_sign(i32 %x) minsize nounwind {
 ; CHECK-LINUX64-LABEL: and32_trunc_16_sign:
 ; CHECK-LINUX64:       # %bb.0:
-; CHECK-LINUX64-NEXT:    andl $32768, %edi # imm = 0x8000
-; CHECK-LINUX64-NEXT:    testw %di, %di
+; CHECK-LINUX64-NEXT:    testw $-32768, %di # imm = 0x8000
 ; CHECK-LINUX64-NEXT:    jg .LBB16_2
 ; CHECK-LINUX64-NEXT:  # %bb.1: # %yes
 ; CHECK-LINUX64-NEXT:    pushq %rax
@@ -733,8 +723,7 @@ define void @and32_trunc_16_sign(i32 %x) minsize nounwind {
 ; CHECK-WIN32-64-LABEL: and32_trunc_16_sign:
 ; CHECK-WIN32-64:       # %bb.0:
 ; CHECK-WIN32-64-NEXT:    subq $40, %rsp
-; CHECK-WIN32-64-NEXT:    andl $32768, %ecx # imm = 0x8000
-; CHECK-WIN32-64-NEXT:    testw %cx, %cx
+; CHECK-WIN32-64-NEXT:    testw $-32768, %cx # imm = 0x8000
 ; CHECK-WIN32-64-NEXT:    jg .LBB16_2
 ; CHECK-WIN32-64-NEXT:  # %bb.1: # %yes
 ; CHECK-WIN32-64-NEXT:    callq bar
@@ -744,9 +733,8 @@ define void @and32_trunc_16_sign(i32 %x) minsize nounwind {
 ;
 ; CHECK-X86-LABEL: and32_trunc_16_sign:
 ; CHECK-X86:       # %bb.0:
-; CHECK-X86-NEXT:    movl $32768, %eax # imm = 0x8000
-; CHECK-X86-NEXT:    andl {{[0-9]+}}(%esp), %eax
-; CHECK-X86-NEXT:    testw %ax, %ax
+; CHECK-X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-X86-NEXT:    testw $-32768, %ax # imm = 0x8000
 ; CHECK-X86-NEXT:    jg .LBB16_2
 ; CHECK-X86-NEXT:  # %bb.1: # %yes
 ; CHECK-X86-NEXT:    calll bar
@@ -767,8 +755,7 @@ no:
 define void @and64_trunc_32_sign(i64 %x) minsize nounwind {
 ; CHECK-LINUX64-LABEL: and64_trunc_32_sign:
 ; CHECK-LINUX64:       # %bb.0:
-; CHECK-LINUX64-NEXT:    andl $32768, %edi # imm = 0x8000
-; CHECK-LINUX64-NEXT:    testw %di, %di
+; CHECK-LINUX64-NEXT:    testw $-32768, %di # imm = 0x8000
 ; CHECK-LINUX64-NEXT:    jg .LBB17_2
 ; CHECK-LINUX64-NEXT:  # %bb.1: # %yes
 ; CHECK-LINUX64-NEXT:    pushq %rax
@@ -780,8 +767,7 @@ define void @and64_trunc_32_sign(i64 %x) minsize nounwind {
 ; CHECK-WIN32-64-LABEL: and64_trunc_32_sign:
 ; CHECK-WIN32-64:       # %bb.0:
 ; CHECK-WIN32-64-NEXT:    subq $40, %rsp
-; CHECK-WIN32-64-NEXT:    andl $32768, %ecx # imm = 0x8000
-; CHECK-WIN32-64-NEXT:    testw %cx, %cx
+; CHECK-WIN32-64-NEXT:    testw $-32768, %cx # imm = 0x8000
 ; CHECK-WIN32-64-NEXT:    jg .LBB17_2
 ; CHECK-WIN32-64-NEXT:  # %bb.1: # %yes
 ; CHECK-WIN32-64-NEXT:    callq bar
@@ -791,9 +777,8 @@ define void @and64_trunc_32_sign(i64 %x) minsize nounwind {
 ;
 ; CHECK-X86-LABEL: and64_trunc_32_sign:
 ; CHECK-X86:       # %bb.0:
-; CHECK-X86-NEXT:    movl $32768, %eax # imm = 0x8000
-; CHECK-X86-NEXT:    andl {{[0-9]+}}(%esp), %eax
-; CHECK-X86-NEXT:    testw %ax, %ax
+; CHECK-X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-X86-NEXT:    testw $-32768, %ax # imm = 0x8000
 ; CHECK-X86-NEXT:    jg .LBB17_2
 ; CHECK-X86-NEXT:  # %bb.1: # %yes
 ; CHECK-X86-NEXT:    calll bar